1. Technical Field
The present invention relates to a light emitting element such as an organic EL element and a light emitting device such as an organic EL device having the light emitting element.
2. Related Art
Recently, as display devices replacing liquid crystal display devices, organic EL (electroluminescence) devices have been developed. In the organic display devices, color display can be performed by regularly disposing organic EL elements each emitting one of three primary colors of red, green, and blue colors. However, when white display is performed by using only the three primary colors, all the organic EL elements corresponding to the three primary colors are configured to emit light. Accordingly, power consumption thereof is increased, and the use life of the organic EL elements decreases. Thus, a method in which color display is performed by using four colors including a white color in addition to the three primary colors has been developed. According to this method, an organic EL element that emits white light is used for white display for which power consumption is the highest of all, and thereby light emission of elements corresponding to other colors can be suppressed. Accordingly, power consumption can be reduced.
Setting a resonant length is important in a case where white light is projected. In the organic EL element, a resonance structure is inevitably formed, and the resonance structure is prominent particularly in a top-emission type element in which a reflective layer is needed in an anode side. Accordingly, light of a specific wavelength is enhanced due to resonance, and it becomes difficult to acquire white light having a low wavelength dispersion property.
Thus, in order to respond to the above-described problem, a method of adjusting a light path length from the reflective layer to a light emission position and a resonant length inside the resonant structure has been reviewed (see JP-A-2006-244712). In addition, a method of changing a layer thickness of a transparent conductive material layer such as ITO constituting the anode of the organic EL element that emits white light has been reviewed (see JP-A-2006-32327).
However, the method disclosed in JP-A-2006-244712 requires a complicated control process, and thus there is a problem in practical implementation. In addition, when the layer thickness of ITO or the like is changed in one element, there is a problem that a manufacturing process thereof is complicated and a manufacturing cost increases.